OFFSET
1,2
COMMENTS
Let r = gamma (the Euler constant, 0.5772...). When {k*r, k >= 1} is jointly ranked with the positive integers, A059555(n) is the position of n and A059556(n) is the position of n*r. - Clark Kimberling, Oct 21 2014
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..2000
Fraenkel, Aviezri S.; Levitt, Jonathan; Shimshoni, Michael; Characterization of the set of values f(n)=[n alpha], n=1,2,..., Discrete Math. 2 (1972), no. 4, 335-345.
Eric Weisstein's World of Mathematics, Beatty Sequence.
FORMULA
a(n) = n + A038128(n).
MAPLE
A001620 := proc(n)
floor((1+gamma)*n) ;
end proc:
seq(A001620(n), n=1..50) ; # R. J. Mathar, Nov 11 2011
MATHEMATICA
t = N[Table[k*EulerGamma, {k, 1, 200}]]; u = Union[Range[200], t]
Flatten[Table[Flatten[Position[u, n]], {n, 1, 100}]] (* A059556 *)
Flatten[Table[Flatten[Position[u, t[[n]]]], {n, 1, 100}]] (* A059555 *)
(* Clark Kimberling, Oct 21 2014 *)
PROG
(PARI) { default(realprecision, 100); b=1 + Euler; for (n = 1, 2000, write("b059555.txt", n, " ", floor(n*b)); ) } \\ Harry J. Smith, Jun 28 2009
(Magma) R:=RealField(100); [Floor((1+EulerGamma(R))*n): n in [1..100]]; // G. C. Greubel, Aug 27 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mitch Harris, Jan 22 2001
STATUS
approved